Tectonic setting and U‐Pb geochronology of the Early Tertiary Ladybird Leucogranite Suite, Thor‐Odin ‐ Pinnacles Area, Southern Omineca Belt, British Columbia
Abstract:The Thor‐Odin ‐ Pinnacles area is a structural culmination in the Shuswap complex of the southern Omineca Belt of the Canadian Cordillera. It comprises amphibolite‐facies rocks that were deformed during Mesozoic‐Paleocene compression and were exhumed in the footwalls of Eocene normal faults during crustal extension. The Ladybird leucogranite suite coincides with the extended terrane in the southern Omineca Belt. It is generally restricted to a midcrustal level which lies in the hanging walls of deep‐seated thr… Show more
“…The duration of the HT conditions and partial melting of the orogenic crust is recorded by the age spread of granites issued from the mid to lower crust and emplaced at higher structural levels. In the Cenozoic Canadian Cordillera, leucogranites cover an age range of more than 10 Myr (Carr, 1992;Parrish, 1995;Vanderhaeghe et al, 1999b;Johnston et al, 2000;Gordon et al, 2008;Kruckenberg et al, 2008). In the Himalaya-Tibet, the age of the oldest leucogranites emplaced in the Higher-Himalayan Crystallines is Oligocene (Deniel et al, 1987;Edwards and Harrison, 1997;Harrison et al, 1999;Chung et al, 2005) that might provide a minimum age for the onset of partial melting beneath Tibet (Vanderhaeghe and Teyssier, 2001b).…”
Section: Relative Timing Of Hp/lt and Ht Metamorphismmentioning
“…The duration of the HT conditions and partial melting of the orogenic crust is recorded by the age spread of granites issued from the mid to lower crust and emplaced at higher structural levels. In the Cenozoic Canadian Cordillera, leucogranites cover an age range of more than 10 Myr (Carr, 1992;Parrish, 1995;Vanderhaeghe et al, 1999b;Johnston et al, 2000;Gordon et al, 2008;Kruckenberg et al, 2008). In the Himalaya-Tibet, the age of the oldest leucogranites emplaced in the Higher-Himalayan Crystallines is Oligocene (Deniel et al, 1987;Edwards and Harrison, 1997;Harrison et al, 1999;Chung et al, 2005) that might provide a minimum age for the onset of partial melting beneath Tibet (Vanderhaeghe and Teyssier, 2001b).…”
Section: Relative Timing Of Hp/lt and Ht Metamorphismmentioning
“…This forward deformation sequence is also followed in our kinematic modeling, and more details are given by Hardebol et al [2007]. Contractional deformation started post-80 Ma farther to west, constrained by the dating of decollement level to polydeformed sillimanite-orthoclase paragneisses [Parrish, 1995;Carr, 1992], and overall shortening ceased at $58 Ma [Fermor and Moffat, 1992;Sears, 2001;van der Pluijm et al, 2006]. Cooling curves suggest rapid uplift and erosion of the Purcell Anticlinorium (just west of the study area) between 65 and 55 Ma [Archibald et al, 1984] and FT T-t modeling for Lewis thrust hanging wall cooling 110-60°C between 75 and 35 Ma.…”
[1] The southern Canadian foreland fold-and-thrust belt (FFTB) (SW Alberta -SE British Columbia) records the interplay between foreland basin evolution with the deforming wedge and thus controls the regionalscale overburden and exhumation history. Overburden estimates are typically based on the assumption that peak burials were reached by sedimentary burial prior to the emplacement of thrust sheets. This study combines organic maturity ranks from a newly compiled catalog with forward thermokinematic modeling to examine this assumption. The organic maturity rank trends correlate not only to sedimentary but also to tectonic burial histories. The forward thermokinematic modeling builds on this combined burial history scenario and shows how required peak burial and temperatures can be achieved with reduced sedimentary overburden when combined with tectonic loading. We thus consider that the overburden was reached during instead of prior to the contraction of the FFTB as result of an integrated sedimentary and tectonic burial history. Thermokinematic modeling also suggests that firstorder steady state temperature conditions prevail during the development of the FFTB. Differently from earlier findings that considered a drop in paleotemperature gradient during the belts growth, steady state conditions reduce the amount of regional overburden required and, consequently, of eroded sediments. Besides tracing the regional evolution, organic maturity ranks are also affected by more local phenomena such as thrust-scale denudation patterns and fluid flow. Citation: Hardebol, N. J., J. P. Callot, G. Bertotti, and J. L. Faure (2009), Burial and temperature evolution in thrust belt systems: Sedimentary and thrust sheet loading in the SE Canadian Cordillera, Tectonics, 28, TC3003,
“…Late Paleocene-Middle Eocene and younger crustal extension and the uplift of mid-crustal metamorphic core complexes in the Omenica belt (Carr, 1992;Lorencak et al, 2001;Price, 1999, 2002;Vanderheghe et al, 2003) was accompanied by westward increasing erosional exhumation of the Foreland thrust and fold belt and the adjacent margin of the undeformed Interior platform. The thickness of strata eroded increases westward from about 2-3 km at the eastern edge of the fold and thrust belt (Magara, 1976;Hacquebard, 1977;Nurkowski, 1984;England and Bustin, 1986a;Issler et al, 1990;Majorowicz et al, 1990), to >8 km in the southern portions of the Front range (Osadetz et al, 2003).…”
Section: Regional Geological and Petroleum Backgroundmentioning
confidence: 99%
“…Younger, Late PaleoceneMiddle Eocene ductile extension and normal faulting developed in the hinterland, west of the transect (Carr, 1992;Lorencak et al, 2001;Price, 1999, 2002;Vanderheghe et al, 2003). This postcompressional crustal deformation event had no direct impact on the architecture of the Subtrap transect, although coeval asthenospheric rise in the hanging-wall of the east-dipping subduction of the Pacific oceanic lithosphere is likely to account for the postorogenic uplift and erosion observed farther to the east in the Alberta foothills, and even in the adjacent foreland autochthon (Burgess et al, 1997).…”
Section: Synorogenic Sediments and Dating Of The Thrust Sequencementioning
confidence: 99%
“…Farther west, in the metamorphic core complexes of the Omineca crystalline belt (Fig. 1), isostatic uplift of mid-crustal rocks is commonly >25 km, and the basal detachment of the Cordilleran foreland thrust and fold is exposed locally at >2 km above sea level (Parrish et al, 1988;Carr, 1992). t e r r a n e P u rc e ll a n ti c li n o ri u m 0 300 km 150 Figure 1 Synthetic map outlining the main structural subdivision of the North American Cordillera in southwestern Canada, and the location of the studied transect.…”
Section: Regional Geological and Petroleum Backgroundmentioning
Résumé -Cinématique et modélisation pétrolière des zones externes des montagnes Rocheuses de l'Alberta à l'ouest de Calgary -Cet article résume les principaux résultats d'une étude intégrée utilisant les données pétrolières de surface et de subsurface, réalisée avec les outils de modélisation pétrolière récemment développés à l'IFP, le long d'un transect recoupant le front des Rocheuses canadiennes de l'Alberta, entre Banff et Calgary. Dans toutes chaînes de montagnes, les compressions sont à l'origine d'un important raccourcissement tectonique, mais aussi d'importants mouvements verticaux impliquant de fortes érosions. Dans un premier temps, nous avons calculé les profils d'érosion, à partir de puits réels ou fictifs, grâce à une modélisation thermique avec le logiciel 1D Genex-Gentec. Ces profils ont permis de reconstruire la géométrie antécompression du bassin flexural crétacé de l'Alberta. Dans un deuxième temps, une modélisation cinématique et thermique directe du front des Rocheuses a été entreprise avec le logiciel 2D Thrustpack. Elle a fourni : -les géométries du bassin depuis les stades préorogéniques jusqu'au stade actuel, en passant par le stade du « bassin flexural » et les différentes étapes de plissement et de chevauchement ; -les fenêtres de maturité des différentes roches mères paléozoïques et mésozoïques en considérant un transfert thermique purement conductif. Ces géométries ont ensuite été utilisées comme conditions aux limites du logiciel Ceres pour modéliser les mouvements et les pressions de fluides, ainsi que la migration des hydrocarbures et leur piégeage dans les anticlinaux. Les résultats de cette étude améliorent considérablement notre compréhension de la chronologie de la genèse et du piégeage des hydrocarbures dans les réservoirs gréseux du Crétacé, et surtout, dans les réservoirs carbonatés du Dévonien-Carbonifère, à partir des roches mères du Crétacé et du Dévonien-Carbonifère.Abstract -Kinematic and Petroleum Modeling of the Alberta Foothills and Adjacent Forelant -West of Calgary -This paper summarizes the main results of an integrated study using surface and subsurface geological data and IFP's basin modeling tools along a regional transect crossing the Alberta foothills and adjacent foreland between Banff and Calgary. Cretaceous subsidence history in the foreland and subsequent erosional profiles in both the autochthon and the allochthon were computed using 1D Genex-Gentec modeling on both real and fictive wells,
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